Enregistrement de données ArrayList après la commutation Activités

Question

J'ai deux ArrayLists dans deux activités. La première ArrayList contient environ 1000 éléments (enregistrés dans un fichier JSON) et la deuxième ArrayList contient 0 éléments.

Il est possible d'ajouter 1 article à ArrayList2 avec « onclick »

Mais quand je ferme l'application des activités wont sauver.

Comment sauvegarder ces modifications?

1.MainActivity:

public class MainActivity extends AppCompatActivity { 

static ArrayList<Recipe> recipeList = new ArrayList(); 
public class ObjList{ 
    public ArrayList<String> recipeList = new ArrayList<>(); 
} 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    mListView = (ListView) findViewById(R.id.recipe_list_view); 
    recipeList = Recipe.getRecipesFromFile("recipes.json", this); 
    String[] listItems = new String[recipeList.size()]; 
    for (int i = 0; i < recipeList.size(); i++) { 
     Recipe recipe = recipeList.get(i); 
     listItems[i] = recipe.title; 
    } 


    final RecipeAdapter adapter = new RecipeAdapter(this, recipeList); 
    mListView.setAdapter(adapter); 
    final Context context = this; 
    mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
     @Override 
     public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
      Recipe selectedRecipe = recipeList.get(position); 
      recipeList.remove(selectedRecipe); 
      recipeList2.add(selectedRecipe); 
      adapter.notifyDataSetChanged(); 

    } 
    }); 
}; 
public void test_onClick(View view) { 
    Intent intent = new Intent(MainActivity.this, TestActivity.class); 
    startActivity(intent); 
} 
private ListView mListView; 
} 

2.Activity:

public class TestActivity extends AppCompatActivity { 
static ArrayList<Recipe> recipeList2 = new ArrayList<>(); 


    public void onCreate(Bundle savedInstanceState) { 
    ListView mListView; 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_test); 
    mListView = (ListView) findViewById(R.id.testlist2); 
    final RecipeAdapter adapter = new RecipeAdapter (this, recipeList2); 
    mListView.setAdapter(adapter); 
    final Context context = this; 
    mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
     @Override 
     public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
      Recipe selectedRecipe = recipeList2.get(position); 
      recipeList2.remove(selectedRecipe); 
      recipeList.add(selectedRecipe); 
      adapter.notifyDataSetChanged(); 
     }});} 
public void test2_onClick(View view) { 
    Intent intent = new Intent(TestActivity.this, MainActivity.class); 
    startActivity(intent); 
}} 

Recipe.class:

public static ArrayList<Recipe> getRecipesFromFile(String filename, Context context){ 
final ArrayList<Recipe> recipeList = new ArrayList<>(); 


try { 
    // Load data 
    String jsonString = loadJsonFromAsset("recipes.json", context); 
    JSONObject json = new JSONObject(jsonString); 
    JSONArray recipes = json.getJSONArray("recipes"); 

    // Get Recipe objects from data 
    for(int i = 0; i < recipes.length(); i++){ 
    Recipe recipe = new Recipe(); 

    recipe.title = recipes.getJSONObject(i).getString("title"); 


    recipeList.add(recipe); 
    } 
} catch (JSONException e) { 
    e.printStackTrace(); 
} 

return recipeList; } 
    private static String loadJsonFromAsset(String filename, Context context) { 
String json = null; 

try { 
    InputStream is = context.getAssets().open(filename); 
    int size = is.available(); 
    byte[] buffer = new byte[size]; 
    is.read(buffer); 
    is.close(); 
    json = new String(buffer, "UTF-8"); 
} 
catch (java.io.IOException ex) { 
    ex.printStackTrace(); 
    return null; 
} 

return json; 
    } 
} 

Answer 1

Si vous application à proximité, les données non sauvegardées est supprimée. Jetez un oeil sur android activity lifecycle. Lorsque l'application est fermée, onDestroy() est appelée. Vous devez remplacer la méthode onDestroy() dans l'activité, qui est supposée enregistrer les modifications.